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    <title>Document</title>
</head>
<body>
    <script>
        for(;;) {
            let username = +prompt('输入用户名')
            let password = +prompt('输入密码')
            if (username === 'ikun'  &&  password === 123456) {
                break
            }
        }
        alert('登录成功')
    </script>
</body>
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